afraid

1. afraid and fear
   In an informal style, be afraid is more common than fear.
   Don’t be afraid, (not Don’t fear) She’s afraid that I might find out.
   Are you afraid of the dark? I’m not afraid to say what I think.
2. I’m afraid
   = ‘I’m sorry’
   I’m afraid (that) often means ‘I’m sorry to tell you (that)’. It is used to introduce apologetic refusals and bad news.
   I’m afraid (that) I can’t help you.
   I’m afraid that there’s been an accident.
   I’m afraid so/not are used as ‘short answers’.
   Can you lend me a pound? I’m, afraid not.
   It’s going to rain. Yes, I’m afraid so.
3. not used before a noun
   Afraid is one of the adjectives that are not usually used before a noun in ‘attributive position’ (see adjectives 1: normal position). Compare:
   John’s afraid.
   John’s a frightened man. (not … an afraid man?)
   For information about -ing forms and infinitives after afraid, see -ing forms 7.• position see age.
   • afraid so/not see so and not with hope, believe, etc
   • be afraid see be and have.
   • with -ing form or infinitive see -ing forms 7: remember, go on etc + -ing or infinitive.
   • see discourse markers.

For more information consult a good dictionary like Langman, Oxford, Merriam Webster, or Collins.